This invention relates to conveyor belt scraper blade assemblies, and particularly such assemblies incorporating scraper blade support arms that permit a reversible scraper blade to be repositioned in place, while the scraper blade remains supported on the support arms.
Adjustable conveyor belt scraper systems that support belt scraper blades in a continuous cleaning relation to an outer return surface of a conveyor belt are shown in Stoll U.S. Pat. No. 4,969,553 issued Nov. 13, 1990 and U.S. Pat. No. 4,402,394 issued Sep. 6, 1983, the disclosures which are incorporated herein by reference.
The belt scraper assemblies, as shown in each of the Stoll patents, are designed to accept scraper blades that have non-circular mounting studs formed at their respective ends. The blades may be reversed to present a new scraper surface to the belt when the original surface is worn. A particularly advantageous reversible blade is disclosed in Stoll U.S. Pat. No. 5,628,392 issued May 13, 1997, which patent is also incorporated herein by reference. The patent of Stoll '392 describes and claims a reversible scraper blade that is designed to be reversed in place, simply by rotating the blade through 180 degrees, rather than also requiring the blade to be switched from end-to-end on the support arms.
Scraper blades for large industrial conveyor belts are necessarily heavy in weight. A blade 100 inches long may weigh as much as 200 pounds. The conventional apparatus for supporting such blades require that the blade itself be removed from its supporting arms or structure, then rotated to present the new wearing surface to the belt, and then reattached. When the blade is freed from the support arms, the weight of the blade must be supported by some means, usually by two persons, one at each side of the belt who must hold the blade, rotate it through 180 degrees, then replace the blade into its support structure. In the case of the blades as shown in the above-identified Stoll patent, the blade supporting stud has a cruciform cross section and must be replaced into a blade holder having a complimentary opening. Such a renewal and replacement process is difficult, not only because of the weight of the blades, but because of the necessity of having to operate in awkward positions and close quarters.
A requirement of any apparatus designed to support the weight of such a blade while it is being rotated in place is that the torque transmitting components must come readily free from the blade supporting arms without jamming or binding. In an arrangement where torque is transmitted through coupling members, any binding that impedes or prevents the release of the blade from the support, to permit in-place rotation, puts the maintenance personnel at risk or, at the least, impedes their performance and increases the time required to make such a change. Further, any such torque transmitting components must, by design, be capable of supporting the scraper blade over long periods of time and under rugged conditions of use, and yet be easily removable for blade rotation.